In a semiconductor device manufacturing process, a resist film is formed on a surface of a substrate such as a semiconductor wafer (hereinafter, referred to as a “wafer”) and then is exposed. Thereafter, the wafer is subjected to a developing process so that a resist pattern is formed on the surface of the wafer. Subsequently, an underlayer film of the resist film is etched using the resist pattern as a pattern mask to form a pattern on the underlayer film.
Incidentally, roughness, i.e., unevenness, may exist on the surface of the resist pattern. Such a roughness of the resist pattern may have an adverse effect on the shape of the pattern of the underlayer film during etching. To address this, there is a case where a process of improving the roughness is performed. For example, there is known a technique for suppressing the roughness of a surface of a resist pattern by irradiating the surface with radiation having a wavelength of 200 nm or less in an atmosphere where an ozone concentration is lower than a predetermined concentration. However, as will be described in detail later, when vacuuming the periphery of the substrate in order to form such an atmosphere, the resist pattern may not have the desired overall shape, which makes it impossible for the resist pattern to function as the pattern mask.